Car seat reversing mechanism with gear



Nov. 10, 1942, a HILL 2,301,279

CAR SEAT REVERSING MECHANISM WITH GEAR Filed Oct. 8, 1940 5 Sheets-Sheet1 1% I ZZWW D film/Z (13%); gm,

Nov. 10, 1942. 2,301,279

CAR SEAT REVERSING MECHANISM WITH GEAR Filed Oct. 8, 1940 5 Sheet-Sheet2 Nov. 10, 1942. o. E. HILL 7 2,301,279

CAR SEAT REVERSING MECHANISM WITH GEAR Filed 001;. 8, 1940 5Sheets-Sheet 4 [72%2270 7 fizz a i/M Patented Nov. 10, 1942 CARSEATREVERSING MECHANISM WITH GEAR Oiva E. Hill, Gardner, Mass, assi'gnorto Heywood-Wakefield Company, Gardner, Mass, a corporation ofMassachusetts Application October 8, 1940, Serial No. 360,253

5 Claims.

This invention relates to reversible car-seat base mechanisms by whichcar seats may be swung around a vertical pivot, and more particularly tomechanisms by which the seat is horizontally shifted during its turningmovement for the purpose of permitting the seat to occupy positionsclose to the adjacent wall of the vehicle when in use without preventingthe'rotation of the seat from one position to another.

The invention represents improvements on the mechanism described andclaimed in my copending application Ser. No. 285,711, filed July 21,1939, pursuant to which Letters Patent No. 2,240,620 were granted May6,1941.

It is an object of the present invention to provide reversing mechanismswhich are more readily and economically manufactured than previousmechanisms designed for similar -purposes, and which smooth the motionof the car seat on its reversing movement, with less tendency to stickor bind at certain stages of the reversing movement.

The car-seat base mechanisms herein shown and described are of the typehaving cam surfaces and cam followers which are effective during areversing movement to shift the seat horizontally so that its centerfollows a predetermined path. In general, inmechanisms of this type,there are points in thereversing movement n of the car seat where theresistance to turning effect is greater than at other points,'this beingdue at least in part to the relative location and configuration of thecam elements and the rotational momentum of the car seat especially whenment. It is desirable that such shifts be gradual or by small steps'soas to promote smoothness of motion in reversing movements of the seat.

According to the present invention, the seat carriage is guided in itsreversing movements by mechanism which includes a rack 'and'pinionarranged to mesh during at least a substantialportion of each reversingmovement. As the pinion rolls along the rack, the successive teeth'actas pivots for theseat carriage and-thus result in a gradual shifting ofthe turning axis.

For a more complete understanding of the invention, reference may be hadto the'following description of certain embodiments thereof, and to thedrawings of which:

Figure 1 is an end elevation of a car-seat structure embodying theinvention.

Figure 2 is a plan view of a portion of eyehicle showing car seatsmounted in the usual manner.

Figure 3 is a section on the line 3-3 of Figure 2, on a larger scale.

Figure 4 is a section on the line 4--4 of Figure 2, on a larger scale.

Figure 5 is a section on the line 5-5 of Figure 2, on a larger scale.

Figure 6 is a sectionon the line 66 ofFigure 3.

Figure '7 is another view of the mechanism shown in Figure 6, on'asmaller scale, the movable parts being shown in a different position ofoperation.

gears illustrated in-Figures8 and 10, and'of'the path followed by thecenter of the seat-"during a reversing movement.

Figures 13 to 16 are'similar diagrammatic representations of variousmodified forms of-rack and gears.

In mounting car seats in a vehicle such as'a railroad coach, it isdesirable that the seatsbe "located as close to the wall of the vehicleas possible so as to provide maximum aisle space. When seats are thusmounted, as indicated'in Figure 2, it is necessary to shift the seattransversely away from the vehicle wall during'the initial portion ofany rotatingmovementof the seat to avoid interference between acornerofthe seatand the vehicle wall as theseat rotates about a vertical axis. Aconsiderable number of guide mechanisms have heretofore been produced toaccomplish such shifting movement by causing lateral displacement of theseat during each reversing movement thereof; but these mechanisms are ingeneral characterized by a tendency to resist rotating movement of theseat unevenly, that is, to permit easy rotation ofthe seat through partsof a reversing movement but to oppose rotating'movement-more-or 'lessstrongly at certain points. The present invention largely obviates thisobjection by the use of a pinion or gear wheel which is adapted to meshwith a concave arcuate rack.

In addition to the sidewise movement of the seat to clear the wallduring the initial and final stages of each reversing movement, it isalso often desirable that the seat have a forward movement, so that whentwo seats are back to back, the backs will clear each other during theinitial portion of the reversing movement of either of the seats.According to the invention, a forward or rearward component of movementcan be provided by means of racks and gears of suitable size and shapeas hereinafter exemplified.

Figure 1 is an end view of a conventional double car seat I having backsI2 and arm-rests I 4. The seat is mounted on a carriage I6 which isslidably supported on the top of a suitable .1 stationary pedestal 20.The car seats illustrated on the drawings are the customary double seatsbut it is evident that the invention is applicable to single seats aswell.

:The stationary pedestal may include a pair of .;parallel rails. 22consisting of angle irons which extend transversely of the seat. Betweenthese rails and flush therewith is a horizontal plate 24 on which thecarriage I6 is slidably supported. Inthe plate 24 is an opening 25,shown in Fig-. ure 6, the edges of this opening serving as cam-.surfaces as hereinafter described. Secured to the seat frame, which isa part of the carriage, t is albar 32 which is disposed within theopening 26 below the level of the top plate 24. Mounted on the bar 32 isa pivot element and cam follow- .er consisting of a roller 34 rotatablymounted 1.,on ,avstud orpbolt 36 which is secured to the b-ar 32 nearone end thereof. The roller 34 normally .engages in one of two sockets40 and 42 which are corners of the opening 26 in the top plate 24. Whenthe pivot roller34 is seated in the socket 40, a similar cam follower 44on the stud 46 is seated in the socket 42, the center points of theelements 34 and 44 being disposed in the longitudinal median of the carseat. I

Mounted beneath the mid-portion of the bar 3 2 in a horizontal plane isa pinion or gear wheel 50. As shown, the gear wheel may be concentricwith the mid-point of the seat. To

rack 52 is transversely offset fromthe longitudinal median of the carseat when the latter is either position of use, and at such times "thegear wheel and rack are not in mesh. 'Whe'n is desired to rotate the carseat from one positionof use to the other, the seat and the seatcarriage are rotated about the axis of the pivot .element 34 during theinitial part of the reversing movement, the roller 44 leaving the socket42 and traveling along the cam edge 56 to maintain the pivot element 34in its socket duringsuch movement. Since the pivot is longitudinal1yoffsetfrom the center point of the seat, 1 the latter moves away fromthe vehicle wall in an arcuate path during the initial portion of thereversing movement. tooth 60 of the gear wheel 50 enters a recess 62 inthe rack 52. The gear wheel thereupon is in meshed engagement with therack and continues in such engagement during the intermediateportion ofthe reversing movement of the This continues until a 1 carriage.movement of the seat away from the vehicle wall seat. As the gear wheel50 rolls along the rack 52, it is held in mesh therewith by the pivotelement 34 which travels along the cam edge 64 and in so doing shiftsfrom the socket 40 to the socket 42. When the pivot element 34 reachesthe socket 42, the gear Wheel 50 is ready to leave the rack 52. Thefinal portion of the reversing movement of the seat thus consists inrotative movement around the axis of the pivot element 34 as it isseated in the socket 42, such movement causing the gear wheel 50 to moveaway from the rack 52 to its final position which is the reverse of thatshown in Figure 6. During such final portion of the reversing movement,the pivot element 34 is maintained in the socket 42 by the cam follower44 which travels along a cam surface 68 on the pedestal top 24. InFigure 7 the path of travel of the center point of the seat is indicatedby a line 10 with arrow heads. This path is pear-shaped and is free fromabrupt .changes in direction, this being an index of the smoothness ofmovement of the car seat and The line 10 also indicates a rapid duringthe initial part of the reversing movement, this movement away from thewall serving to clear the corner of the seat from contact with the wall.There is also a forward movement of the seat during such initial portionof the reversing movement, this being advantageous in helping to preventinterference between the backs of the reversing seats and the backs ofadjacent seats in the vehicle. Thus the seats can be mounted moreclosely together and more seats can be put in a coach of given length.

Suitable mechanism is provided for releasably holding the seat in eitherof its positions for use. As shown, the bar 32 is provided at one endwith a fan-shaped end element I2 which is adapted to fit into a recess14 in a fitting 16 which is secured to one of the rails 22 of thepedestal. The element 12 is mounted on the end of a plunger which isaxially slidable in the vbar 32 and is pressed by a suitable spring 82to push the end element 12 yieldingly against the fitting 16. When theend of the seat is pulled or pushed to start the reversing movement, the

I end element 12 rides out of the recess 14 against the pressure of thespring 82.

After this initial resistance is overcome, the seat swings easily untilit reaches its other position of use, whereupon further rotation of theseat is stopped by the engagement of the element 44 in the socket shownin Figures 8 and 9, this mechanism including a stationary pedestalhaving a pair of angle irons I00 as rails between which is a horizontalplatform I02 set fiush with the upper surface of the rails. The platformI02 has therein an opening I04, the edges of which serve as cam surfacesto guide a pair of cam followers 34 and 44 as hereinafter described.Also mounted on the pedestal is a concave arcuate rack I06, this rackbeing preferably below the platform' I02 as indicated in Figure 9. Asshown, the rack is semi-circular, the center of curvature of the pitchcircle of the rack being the center of the seat carriage when the latteris in either position for use. in q The seat carriage is partiallymdicatedby a pair of horizontal frame members 'IIO which "normally reston the angle irons I00. These frame members are secured by welding orotherwise to 'a pair of oval supporting plates II2 to which is secured aspacing bar 32 by means of a pair of stud bolts 36 and 46 which areconcentric with the cam followers 34 and 44 respectively. Rigidlysecured to the under side of the bar 32 is a pinion I16, this pinionbeing half the diameter of the rack I06, that is to say, the pitchcircle of the pinion II6 has a diameter half that of the pitch circle ofthe rack I06. The pinion I I6 is so arranged with respect to the bar 32that its center is on the longitudinal median of the seat carriage andthe center point of the seat carriage is on the pitch circle of thepinion. The cam edges about the aperture I04 are shaped so as tocooperate with the cam followers'34 and 44 to maintain the pinion I I6in mesh with the rack I06. When the seat is in either position of use,

'the cam followers 34 and 44 engage in corners or sockets I in the camsurfaces. During the first half of a reversing movement, the camfollower 44 travels along a curved cam surface I22 as the pinion I I6moves along the rack I06. During the with the rack I66 during the entirereversing movement. Since the pitch diameter of the pinion is just halfof the pitch diameter of the lack, the center point I of the seat whichis on the pitch circle of the pinion describes a hypocycloid which is inthe form of a straight line coinciding with the transverse median of thepedestal. This means that during the first'half of a reversing movementthe center point of the seat moves directly away from the vehicle wallin a straight path, the rate of such movement being at a maximum at thebeginning of the reversal of the seat and decreasing to zero when halfof the reversing movement has been completed. During the last half ofthe reversing movement, the center point of the seat moves back towardthe wall at an increasing speed until it reaches its original positionwhen the reversing movement is completed, the foregoing rates ofmovement of the center point of the seat being predicated on a constantangular speed of rotation of the seat during a reversing movement.

Figures 10 and 11 illustrate another modified form of the invention. Astationary pedestal is shown including a pair of rails I40 between whichis secured a platform I42, the top surface of this platform beingslightly below the top surfaces of the rails I40 as indicated in Figure11. Mounted on the pedestal beneath the platform I42 is a concavesemi-circular rack I44 the center of which is at the center of thepedestal. The platform I42 is provided with an opening I46 having asemi-circular convex cam surface I48 which is concentric with the rackI44. The seat carriage is represented in Figure 10 by a pair of framemembers I50 connected by a central longitudinal frame member I52.Secured to the latter is a circular bearing plate I54 which rests on thetop point of the seat being indicated in each case.

- circle.

'seat carriage during reversing movements there- 'of. Concentric withthe circular plate I54 is a pinion I which is fixed on the transverseframe member I52, the center of the pinionbeing on the longitudinalmedian of the seat carriage. Also concentric with the plate I54 andpinion I60 is a cam follower I62 which is preferably rotatable and whichbears against the convex cam surface I48 so as to maintain'the pinionI60 in mesh with the rack I44. The pitch diameter of the pinion I60 isone-half the pitch diameter of the rack I44. The center point I of theseat is directly above a point on the pitch circle of the pinion I60, sothat when the pinion moves on the rack I44, the point I10 describes ahypocycloid I12 which, as indicated in Figure 12, is a straight linecoinciding with the transverse median of the pedestal. Thus the seatduring the first half of any reversing movement moves away from thevehicle wall, the center point of the seat moving in a straight lineparallel to the pedestal rails I40. During the last half of anyreversing movement the center point of the seat moves back toward thevehicle wall until it reaches its originalposition when the reversingmovement is I completed.

Figures 13 to 16 represent diagrammatically a few of the many variationsof forms the rack and pinion structure for reversing car-seat bases maytake, the paths of movement of the center In Figure 13 the rack I is acomplete circle within which rolls a pinion I82 having a pitch diametertwo-thirds that of the rack. The center I'I0 of the seat is over thecenter of the pinion. Hence the path described by the center Ill) is acircle I84. This movement is useful in certain special cases, but is notdesirable for the ordinary car seat as the initial shifting movement isalong the wall rather than away from it.

In the mechanism indicated in Figure 14 the pinion I86 rolls on a rackI33 which is 120 of a As is evident from the curve I88, the initialshifting movement of the seat is rapidly away from the wall, with asmall rearward component.

In Figure 15 a pinion I90 rolls within a circular rack I92 but is offsetfrom the center so that only five-sixths or 300 of the rack istraversed. The ratio of diameters of the pinion and rack is five toeight. During initial reversing move ments, the seat has an outwardshift away from the wall, the shifting movement having also a decidedforward component, as indicated by the curve I94, which is particularlyadvantageous in the case of seats having backs adjustable to variousangles of inclination.

Figure 16 illustrates a pinion I96 rolling on a I rack I66 which is inthe form of a semicircle havsurface of the platform I42 so as to carrythe 7 ing straight extensions at the ends, the total length of the pitchcontour of the rack being equal to the circumference of the pitch circleof the pinion. As indicated by the curve 200, the seat center I70 movesrapidly away from the wall during initial portions of reversingmovements, the shifting movement having a relative- 1y small forwardcomponent.

In the foregoing discussion of reversing move ments it is assumed thatthe seat itself is mounted on the seat carriage to face in the directionindicated by the legend Front in Figures 12 to 16. A seat so mountedfaces the vehicle wall during the mid-portion of each reversingmovement. The seats could be mounted on the carriages to face in theopposite direction, in which case they would face the aisle duringreversals and the forward and rearward components of shifting movementswould be just the opposite to those hereinbefore described, but it iscustomary practice to mount the seats on the carriages as indicated onthe drawings.

It is evident that various modifications and changes may be made in theembodiments of the invention herein shown and described withoutdeparting from the spirit or scope thereof as defined in the followingclaims.

I claim:

1. A car-seat base comprising a stationary pedestal, a seat carriageslidable and reversible thereon, and means for guiding reversingmovements of said carriage on said pedestal, said means including apivot element on said carriage longitudinally offset from the centerpoint thereof, a socket on said pedestal in temporary engagement withsaid pivot element during the initial portion of a reversing movement, aconcave arcuate rack mounted on said pedestal in a horizontal plane, agear wheel carried by said carriage and movable into meshing engagementwith said rack by rotation of said carriage about its pivot, meansincluding said pivot and a cam surface on said pedestal for maintainingsaid gear wheel and rack in mesh during the intermediate portion of areversing movement of the seat, and a second socket on said pedestaladapted to receive said pivot element for the final portion of thereversing movement of the seat.

2. A car-seat base comprising a stationary pedestal, a seat carriageslidable and reversible thereon, and means for guiding reversingmovements of said carriage on said pedestal, said means including a gearwheel normally disposed in a horizontal plane and concentric with thecenterpoint of the seat, a concave arcuate rack mounted on said pedestaland transversely offset from the horizontal median of the seat so as tobe out of mesh with said pinion when the seat is in either of its normalpositions for use, means for causing transverse shifting movement of theseat carriage during the initial portion of its reversing movement tobring said gear wheel into mesh with said rack for the intermediateportion of said reversing movement, and means for causing shiftingmovement of the seat carriage during the final portion of its reversingmovement to bring said gear wheel away from said rack to position on thelongitudinal median of the seat.

3. A car-seat base comprising a stationary pedestal, a seat carriageslidable and reversible thereon, and means for guiding reversingmovements of said carriage, said means including 'a gear wheel mountedon said carriage in a horizontal plane and concentric with thecenter-point of the seat, a, pivot element mounted on the carriage andlongitudinally offset from the centerpoint thereof, a pair of sockets onsaid pedestal one of which is operatively engaged by said pivot elementduring the initial portion of a reversing movement, the other socketbeing engaged by said pivot element during the final portion of areversing movement, an arcuate rack engaged by said gear Wheel duringthe intermediate portion of a, reversing movement while said pivotelement shifts from one side socket to the other, cam means on saidcarriage and pedestal for maintaining said pivot element in said socketsduring the initial and final portions respectively of a reversingmovement, and a cam surface on said pedestal engaged by said pivotelement during its movement from one socket to another to maintain saidgear wheel in mesh with said rack during the intermediate portion of areversing movement.

4. A car-seat base comprising a stationary pedestal, a seat carriageslidable and reversible thereon, and means for guiding reversingmovements of the carriage on the pedestal, said guiding means includingcam and follower means effective during the reversing movement of thecarriage to confine such movement to rotation successively aboutstationary axes offset from the center-point of the seat respectivelyduring the initial and final portions of said movement, said guidingmeans also including a rack and pinion device having members mounted onsaid pedestal and carriage respectively and interengageable to assist inguiding the carriage during an intermediate portion of said reversingmovement.

5. A car-seat base comprising a stationary pedestal having an openingforming a cam edge in the top thereof, a seat carriage slidable andreversible on said top, and means for guiding the reversing movements ofsaid carriage, said guiding means including a pair of spaced camfollowers mounted on said carriage and projecting into said opening toengage and travel along said cam edge at opposite sides of said opening,a rack mounted on said pedestal in a plane parallel with said top, and apinion secured to said carriage and movable therewith in the plane ofsaid rack, said rack and pinion being arranged to maintain one of saidfollowers in contact with said cam edge and to be kept in mesh by saidone follower during a portion of each reversing movement of thecarriage.

OIVA E. HILL.

